This is a project to define ways of enhancing orientation and mobility skills of the blind through the use of electronic assistive devices. The objective of this study is to define and specify the optimum form of information presentation of the spatial nature of the environment to a blind person through the auditory and tactile senses. The project builds upon prior experiences gained from the recent introduction of electronic devices to the rehabilitation field, and attempts to use this experience to better understand the human perceptual-motor processes involved in volitional movement in order to develop improved mobility aids. This project will rely heavily upon interactive computer simulation of information displays, in which the subjects' actions are monitored and used to control the display, for several reasons: flexibility and ease of modification of display parameters between and during experiments; freedom from the need to design, build, and test complex devices in order to test hypotheses; provision of a well defined and controlled experimental environment; and a powerful means of monitoring subjects' search strategies while performing mobility related tasks. The subjects will be set tasks within the simulated environment, and their function will be monitored for various forms of display, and variation of parameters. The results of this project will yield engineering design information that will be directly applicable to the development of improved sensory aids for the blind.